SHEAR BEHAVIOR OF HIGH STRENGTH SELF COMPACTING CONCRETE BEAMS

Abstract

This research presents an experimental study to investigate the shear behavior of high strength self-compacting concrete slender beams. The experimental program includes testing seven beams with constant size of (150mm height ×125mm width×1000mm length) to study the effect of shear span to effective depth ratio (a/d), longitudinal reinforcement ratio (ρw) and shear reinforcement ratio (ρv) on shear behavior for these beams. The experimental results showed that, increase shear span to effective depth ratio (a/d) has pronounced effect on decreasing diagonal cracking load and ultimate shear strength and increasing the ductility ratio, as (a/d) increase from 2.5 to 3.0, the decreases in diagonal cracking load and ultimate shear strength are with percentages of 17.8% , 21.6% respectively, while the ductility ratio increase with percentage of 16.7%. Also the results showed that the longitudinal reinforcement ratio (ρw) has significant effect on the gain in shear bearing capacity and ductility ratio, as increasing of longitudinal reinforcement ratio from 3.191% to 6.383% the increases in diagonal cracking load, ultimate shear strength and ductility ratio are with percentages of 43.8%, 46.6% and 37.0% respectively. Furthermore the results revealed that the vertical shear reinforcement has the major effect in improvement the shear behavior of these beams, however, using shear reinforcement (ρv) with percentage of 0.502% results in increase diagonal cracking load, ultimate shear strength and ductility ratio with percentages 50.7%, 63.6% and 48.1% respectively as compared with beam without shear reinforcement. Also presence of vertical shear reinforcement changed the mode of failure from the brittle to ductile.